Hey guys I have been brewing up some ideas for my biodiesel/vegi-oil conversion and think I have an idea of what it will take. First of all I will be running dual tanks on an m1008, dual electric fuel pumps, valve selector, no mech pump, and all polyurethane reinforced lines from tanks to intake, and already have all the parts to do so. Well my question is in regard to the pass side tank that I will be using for the vegi oil to run off of after its warmed up. I got to thinking today, well the heater core I have is narrower than the fuel tank, and have eliminated the heater under the dash so I will already have a few ports open in the radiator that will be usable. Why not just put the heater core inside the fuel tank on the front of it by the fuel pickup with the ports sticking out so I can run the heating lines to them to have a built in heater for my veg oil tan, with the tank and lines where they stick out of the tank being sealed and all. What do you guys think, I know it will work, but wanted to ask about the whole welding on a fuel tank. BTW the tank is from a diesel truck, is completely empty, and has already been drained and all the fuel washed out. Any problems to foresee or things I should look out for?